I've gone on personal missions to "fix" Perl's hackish
OO. Object::Lexical is one attempt - instance data
is held in lexicals and accessors/mutators are
closures, created with Sub::Lexical.
To quote the POD:

Different syntax for instance data than other variables
(my, local) makes refactoring code hard - every "$foo" must be changed to "$self->{foo}" manually.

No help from "use strict" and "use warnings" about
only using a name once. None of the protection of requiring
that a variable be declared first. In short, hash entries
don't get all of the diagnostic helpfullness perl gives
lexicals.

CPU overhead for hash lookups, memory overhead for
storing hashes.

Each object is given its own stash (namespace) which
inherits from the namespace of the current package.
The stash is populated with closures. Viola!
Thanks to Juerd, by the way, who suggested
creating things and stuffing them into stashes instead
of sticking an AUTOLOAD to proxy to methods stored in
hashes.

Then there is typesafety:
http://search.cpan.org/~swalters/typesafety-0.04/
with its massive userbase of 0 users. This cultural
divide miffs me - no Java user would ever consider
a language that didn't have typesafety, and no Perl
programmer would ever willingly use typesafety.
Actually, I know (or know of atleast) a lot of people that
lost their Perl jobs and had to get Java jobs, and now
would never go back to Perl because of things like the
lack of typesafety and other OO hackishness in Perl,
which just goes to show, people don't know what's
good for them.